#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;
int& add(int a, int b)
{
    int c = a + b;
    return c;
}
int main()
{
    int& n = add(1, 2);
    cout << "add(1, 2) = " << n << endl;
    add(3, 4);
    cout << "add(1, 2) = " << n << endl;
    return 0;
}